An electric power converter having an electric power conversion circuit such as a DC-DC converter or an inverter is mounted on an electric vehicle or a hybrid vehicle. Since such an electric power converter is for adjusting and controlling electric power for driving a motor of the electric vehicle, etc., the power handled by it is very large. Thus, there is a large amount of heat generated from components constituting the electric power conversion circuit (for example, a reactor, a capacitor, and etc.) during operation of the electric power converter. In order to operate the electric power converter stably, it is necessary to operate it while maintaining a proper temperature thereof by cooling the components of the electric power conversion circuit.
The electric power converter has a structure such that a plurality of components constituting the electric power conversion circuit (hereinafter, also referred to as circuit components) are housed inside the case. Further, cooling passages where fluid such as coolant or cooling water passes through are formed inside the case. The temperature of each circuit components is maintained at an appropriate temperature by heat being exchanged between the fluid supplied from the outside that passes through the cooling passages and the circuit components.
Since the electric power converter is disposed in a limited space of the electric vehicle, etc., it is required that overall form is compact. Therefore, it has become common that the electric power conversion circuit is not housed in a state where all the circuit components are aligned along a single horizontal plane in the case, but is housed in a state where the circuit components are divided into an upper space and a lower space in the case. As a result, the cooling passages for cooling the circuit components are also respectively formed on the upper space and the lower space in the case (refer to Japanese Patent Application Laid-Open Publication No. 2012-210022).
There are four tubes connected to the case from the outside for feeding and discharging the fluid into and out from the cooling passages in the electric power converter disclosed in the above Publication No. 2012-210022. That is, it has a structure that four tubes consisting (1) a tube for feeding the fluid from outside the case to the upper space cooling passages, (2) a tube for discharging the fluid outside of the case from the upper space cooling passages, (3) a tube for feeding the fluid from outside the case to the lower space cooling passage, and (4) a tube for discharging the fluid outside of the case from the lower space cooling passages are respectively protrude toward the outside from side surfaces of the case.
Furthermore, tubes for connecting the upper space cooling flow passages and the lower space cooling flow passages are disposed on the outside of the case. As a result, many other tubes are routed around the case, and these tubes would interfere with other devices that are disposed around the electric power converter. In other words, in a case where the conventional electric power converter is mounted on the electric vehicle, etc., routing of the plurality of tubes where the cooling fluid passes becomes extremely difficult in the conventional electric power converter disclosed in the Publication No. 2012-210022.